Originally Posted by nealtw
Let's not go to panic mode to fast. He said, he understude the diagram and followed correctly, that only left the switch. I would not have suggested hooking up the lights in case he had a 220 situation but more likely a mistake would have been 2 sources from the same breaker.
Sometimes the best answer is nothing better than better questions.
One time I figured out how many ways you could hook one, two or three wires to an outlet that has hot, neutral and ground.
Just listing them was exhaustive and amounted to about 30 ways, which means your odds of getting it right by guessing was about 1 in 30.
Of course, DIYers know stuff (some right and some wrong) and so the odds are considerably better but still in favor of Murphy's Law.
IIRC a book on troubleshooting said to take one guess and then get back to basics and follow the tried and true troubleshooting routines, tedious and slow as they may be.
You trade slowness for certainty.
My guesses, and those of people on forums who fix by replacing parts, are hardly ever right so almost immediately I start checking the basics.
It follows from this that learning the basics will almost always serve you, sooner or later. And knowing these means you hardly ever panic.
A few times I ran into 'impossible' situations, which I soon learned meant that I was assuming something that was not true. Finding that unconscious assumption of mine was real work.